Agradecimientos:
The work of the first and fourth author was supported by (CMUC) Department of Mathematics, University of Coimbra. The second author would like to thank Unidade de investigação (Matemática e Aplicações) da Universidade de Aveiro. The work of the third author was supported by Dirección General de Investigación (Ministerio de Educación y Ciencia) of Spain under Grant MTM 2006-13000-C03-02. The work of M.N. Rebocho was supported by FCT, Fundação para a Ciência e Tecnologia, with Grant ref. SFRH/BD/25426/2005.

Resumen:

In this paper we extend the concept of coherent pairs of measures from the real line to Jordan arcs and curves. We present a characterization of pairs of coherent measures on the unit circle: it is established that if (μ0,μ1) is a coherent pair of measures on In this paper we extend the concept of coherent pairs of measures from the real line to Jordan arcs and curves. We present a characterization of pairs of coherent measures on the unit circle: it is established that if (μ0,μ1) is a coherent pair of measures on the unit circle, then μ0 is a semi-classical measure. Moreover, we obtain that the linear functional associated with μ1 is a specific rational transformation of the linear functional corresponding to μ0. Some examples are given.[+][-]